Long-term inhibition of the central alpha(2B)-adrenergic receptor gene via recombinant AAV-delivered antisense in hypertensive rats

BACKGROUND: Salt-induced hypertension is mediated via the alpha(2B)-adrenergic receptor (AR) subtype. In alpha(2B)-AR gene knockout mice, blood pressure (BP) does not rise with salt loading, and in rats with salt-induced hypertension, BP decreases transiently with antisense (AS) treatment targeting the alpha(2B)-AR gene. The present experiments were designed to explore the possibility of gene transfection in the brain by intracerebroventricular (ICV) delivery of AS-DNA via adeno-associated virus (AAV) to prolong alpha(2B)-AR inhibition and hence reversal of salt-dependent hypertension. METHODS: A recombinant AAV (rAAV) vector preparation encoding the alpha(2B)-AS fragment (previously tested in vitro for inhibition of alpha(2B)-AR protein production in cells) and containing green fluorescence protein (GFP) for visualization was injected ICV into subtotally nephrectomized, salt-fed rats. Control rats received rAAV-GFP (n = 8 per group). RESULTS: We observed that BP rose from a baseline of 120 +/- 10 to 184 +/- 12 mm Hg. Injection of rAAV-alpha(2B)-AS produced a 35 +/- 12 mm Hg fall in BP, lasting without evidence of diminishing for at least 16 days, whereas rAAV-GFP-injected rats showed a continued rise in BP. Rats treated with rAAV-alpha(2B)-AS treated had a 45% to 65% decrease in alpha(2B)-AR protein levels in key regulatory regions of the brain. Neither group had signs of immunologic response to the virus injection. CONCLUSIONS: These results indicate that our construct, when given by ICV means, could reach multiple sites of the central nervous system relevant to BP regulation and could safely inhibit the central alpha(2B)-adrenergic receptor, thereby achieving prolonged reversal of salt-induced hypertension.     

Effectiveness of ezetimibe alone or in combination with twice a week Atorvastatin (10 mg) for statin intolerant high-risk patients

This study was undertaken to investigate the effect of ezetimibe (10 mg/day) alone or in combination with atorvastatin (10 mg twice a week) on hypercholesterolemia in 56 high-risk patients intolerant to daily statin use. Ezetimibe monotherapy was well tolerated (2 withdrawals) and induced a mean reduction in low-density lipoprotein (LDL) cholesterol of 20% (p <0.05) at the third month. However, of the 54 patients still taking ezetimibe, only 5 (9%) were at their LDL cholesterol targets. Atorvastatin 10 mg twice a week was then added to ezetimibe and was well tolerated (3 withdrawals). This combination reduced LDL cholesterol (in a treatment-based analysis) by 37% compared with baseline (p <0.001), with 43 (84%) patients reaching their LDL cholesterol goals. When patients (n = 34, 25 men) with baseline serum creatinine values in the upper 2 tertiles were analyzed separately, there was a significant (p = 0.041) decrease in serum creatinine levels after 6 months of treatment. In conclusion, the combination of ezetimibe plus atorvastatin 10 mg twice a week might be a therapeutic option for high-risk patients intolerant to daily statin monotherapy.     

Hypertensice response to saline microinjection in the area of the nucleus tractus solitarii of the rat

We investigated the blood pressure response elicited by microinjection of various hypertonic solutions into the area of the nucleus tractus solitarii (NTS) of the brainstem, an area rich in catecholaminergic neurons. Equiosmolar solutions of NaCl, dextrose, LiCl and KCl were employed. NaCl produced a prolonged blood pressure rise; LiCl and normal saline produced a similar rise of short duration; and KCl produced epileptic-type seizures with postictal hypertension. Dextrose had no effect and neither had NaCl microinjection in areas relatively distant from the NTS. The rise in blood pressure was not reversed by a vasopressin antagonist injected systemically, but was totally abolished by systemic α-adrenergic blockade with phentolamine. These findings suggest that sodium can cause hypertension by direct stimulation of the central sympathetic nervous system without participation of peripheral mechanisms such as fluid volume expansion or alteration of the vascular wall.